Adjustable, self-aligning joint for pliers, shears and the like

ABSTRACT

A tool including a pair of members mounted for relative rotation with respect to each other about a pivot column in which said pivot column is nonfrictionally, rigidly mounted with respect to one of said members and rotatably mounted with respect to the other of said members and in which said pivot column and said members include means for maintaining one of said members in a predetermined pivotal relationship with the other said member during operation thereof.

United States Patent Inventor Eugene 1F. Smith Denver, Colo.

June 5, 1968 Aug. 31, 1971 Rocky Mountain Dental Products Co.

Denver, Colo.

Appl. No. Filed Patented Assignee ADJUSTABLE, SELF-ALIGNING JOINT FORPLIERS, SHEARS AND THE LIKE 2 Claims, 11 Drawing Figs.

us. c1 81/416, 30/266, 287/101 11111. or B25b 7/06, Fl6c 1 1/00 FieldofSearch 81/416,

[56] References Cited UNITED STATES PATENTS 3,289,296 12/1966 Hedstromet a1. 287/101 X 3,355,200 11/1967 Storch 287/101 2,596,767 5/1952Erickson 30/266 3,331,132 7/1967 Miles etal. 30/266 PrimaryExaminer-R0bert C. Riordon Assistant Examiner-Roscoe V. Parker, Jr.All0rney-Sheridan and Ross ABSTRACT: A tool including a pair of membersmounted for relative rotation with respect to each other about a pivotcolumn in which said pivot column is nonfrictionally, rigidly mountedwith respect to one of said members and rotatably mounted with respectto the other of said members and in which said pivot column and saidmembers include means for maintaining one of said members in apredetermined pivotal relationship with the other said member duringoperation thereof.

PATEHTEH was] I971 SHEEI 1 BF 2 INVENTOR EUGENE E SMITH ATTORNEYS amz 'mI ADJUSTABLE, SELF-ALIGNING JOINT FOR PLIERS, SHEARS AND THE LIKEBACKGROUND OF THE INVENTION Heretofore, many joints have been proposedfor tools and the like including pivotally mounted members. However,none of such tools has provided a joint having an adjustable operatingtorque which will remain substantially unchanged even though one of themembers has been pivotally operated with respect to the other one alarge number of times. For example, it has been found that the operatingtorque for joints of tools of this type changes, at least gradually,with each pivotal movement of one of the members relative to the otherone. Further, it has been found desirable not only to establish andmaintain a predetermined operating torque for a tool of this type butalso at the same time to insure that the pivotally mounted members arealways disposed with respect to each other in a predetermined pivotalrelationship. This latter item is particularly important for pliers usedto handle or position small items such as arch wires and the likeinvolved in the field of orthodontia and also for precision'shears.

SUMMARY OF THE INVENTION This invention relates generally to a joint fora tool including a pair of pivotally mounted members and morespecifically to a joint for a tool such as pliers, shears and the likein which said pivotally mounted members rotate about a pivot columnwhich is nonfrictionally rigidized with respect to one of said membersbut mounted for pivotal movement with respect to the other said member,and said pivotally mounted members and said pivot column including meansfor maintaining one of said members in a predetermined pivotalrelationship with the other said member during operation thereof.

It has been found, however, that a joint for a tool having a pair ofpivotally mounted members may be provided which operates continuously ata predetermined torque level by mounting said members about a pivotcolumn which is nonfrictionally rigidized with respect to one of saidmembers but mounted for pivotal movement with respect to the other ofsaid members. Further, a precise, predetermined pivotal relationshipbetween said members may be continuously maintained through the use of apivot column having a pair of conically shaped portions formed on thesurfaces thereof in combination with conically shaped bore portionsformed in said pivotal members wherein the conically shaped portionsformed on said pivot column are disposed in mating contact with theconically shaped bore portions formed in said members. Through the useof the joint structure of this invention, the amount of torque is notonly infinitely adjustable butif the torque level has changed for anyreason whatsoever, it is a simple matter to adjust the joint structureof this invention and reset the torque to the desired level withoutdisassembling the joint structure. Additionally, the torque issubstantially constant for any open or closed position of the membersinvolved.

Moreover, due to the large bearing areas provided, a joint structure asdescribed herein has an increased life since the force holding the partstogether is distributed over a larger wear area. I

Accordingly, one of the principal objects of this invention is toprovide an improved joint for a tool including a pair of members mountedfor relative rotation with respect to each other.

Another object of this invention is to provide a joint for a tionship ofone of said members with respect to the other one is preciselymaintained over a large number of pivotal operation of said members.

Another object of this invention is to provide atool includ ing a pairof members mounted for relative rotation with respect to each otherabout an axis and abutting in a plane perpendicular to said axis, theimprovement being the tool comprising in combination a bore formed ineach of said members, each of said bores havinga longitudinal axisconcentrically disposed with respect to the aforesaid axis, each of saidbores having a portion forming a conically shaped bearing seat; and apivot column, said pivot column being nonfrictionally rigidized withrespect to one of said members and mounted for relative rotation withrespect to the other of said members, said pivot column comprising ascrew portion and a nut portion, said screw portion having a conicallyshaped portion formed thereon and disposed in mating contact with theconically shaped bearing seat formed on. one of said members, and saidnut portion having a conically shaped portion formed thereon anddisposed in mating contact with the conically shaped bearing seat formedin the other of said members.

DESCRIPTION OF THE DRAWINGS.

The foregoing and other objects and advantages of this invention willbecome apparent from the specification and accompanying drawingswherein:

FIG. l is a plan view of a plier-type tool incorporating the jointconstructed in accordance with the subject invention;

FIG. 2 is a plan view of a portion of one of the members shown in FIG.ll;

FIG. 3 is a bottom plan view of the member shown in FIG. 2;

FIG. 4 is a plan view of a portion of the other one of said membersshown in FIG. I;

FIG. 5 is a bottom plan view of the member shown in FIG. 4;

FIG. 6 is a partial cross-sectional view taken along line 66 in FIG. 1;

FIG. 7 is an exploded view of a pivot column used in a tool constructedin accordance with the subject invention;

FIG. 8 is a plan view of the nut portion of the pivot column shown inFIG. 7;

FIG. 9 is a bottom plan view of the nut portion shown in FIG. 3;

FIG. 10 is a bottom plan view of the screw portion of the pivot columnshown in FIG. 7;

FIG. l I is a view similar to that shown in FIG. 6 showing an additionalembodiment of a joint constructed in accordance with the subjectinvention; and

FIG. 12 is a perspective view of a hollow, frustoconically shapedbushing shown in FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings,in FIGS. 1-10 is shown one embodiment of a tool 20 incorporating a jointconstructed in accordance with the subject invention. The tool 20, whichis depicted as a pair of pliers, includes a pair of members 22 and 2mounted for relative rotation with respect to each other about an axis26, see FIG. 6, and abutting in a plane perpendicular to said axis 26.Each of the members 22 and 2d has a bore 28 and 30, respectively, formedtherein. Each of said bores 2b and 30 has a longitudinal. axisconcentrically disposed with respect to the aforesaid axis 26. Each ofsaid bores 28 and 30 also has a portion forming a conically shapedbearing seat 32 and 34, respectively.

The tool 20 also includes a pivot column 36 which is nonfrictionallyrigidized with respect to one of said members, such as member 22, andmounted for relative rotation with respect to the other of said members,such as member 24. The pivot column 36 comprises a screw portion 38 anda nut portion 40. The screw portion 38 has a conically shaped portion 42formed thereon which is disposed in mating contact with the conicallyshaped bearing seat 32 of bore 28. The nut portion 40 of said pivotcolumn 36 has a conically shapedportion M formed thereon which isdisposed in mating contact'with a conically shaped bearing seat 34 ofbore 30. The pivot column 36 also includes a boss means such as theaxially extending boss portions 46 formed on one end of the nut portion40, Each of said boss portions 46 are disposed within a cortorque thatwill be encountered in operating or pivoting one of responding recessportion 48 formed in the upper surface of member 22 as shown in FIGS. 2and 6. The pivot column 36 also includes a tool-receiving means such asthe slot or recess 50 formed in the head of the screw portion 38.

The assembly of the tool shown in FIGS. 1-10 is now described. For aright-handed person, the member 24 is preferably held in the left handin the position indicated in FIG. 4. The nut portion 40 is then insertedwithin the bore of member 24. The forefinger of the left hand is thenpositioned above the assembled nut portion and member 24. The assemblednut portion and member 24 are inverted and member 22, which is held inthe right hand in the position indicated in FIG. 3, is then placed inoverlying relationship with respect to the assembled nut portion 40 andmember 24 until the bores of said members are aligned and thebossportions 46 of the. nut portion 40 are disposed within the recessportions 48 formed in member 22. Next, the screw portion 38 is insertedwithin the bore 28 of member 22 and through the use of a suitable tool(not shown) such as a screwdriver, the screw portion 38 is threaded intothe nut portion 40. The amount of such threading depends upon the degreeof force desired to hold the mating surfaces 52 and 54, respectively, incontacting engagement with each other. The degree of force with whichmembers 22 and 24 are held together determines the amount of torquerequired to operate or pivot one of the members relative to the othermember.

It will be readily appreciated that as a result of the boss portions 46being disposed within the recess portions 48 there will be no transferof friction between member 24, which is mounted for relative rotationwith respect to the pivot column 36, and the pivot column 36 duringoperation and use of the tool that would result in the nut portiontightening or loosening with respect to the screw portion. This uniqueadvantage is achieved by nonfrictionally rigidizing the pivot column 36with respect to member 24. In this connection, it will be understoodthat mere reliance upon the frictional forces generated by the matingcontact between the threaded parts of the nut 40 and the screw portion38 are entirely inadequate to achieve the desirable benefit obtainedherein,

The use of the conically shaped bearing seats 32 and 34 formed,respectively, in the bores 28 and 30 in combination with the conicallyshaped portions formed on the pivot column are highly beneficial inmaintaining a predetermined pivotal relationship between the members 22and 24. Where exacting positioning work or tensioning of a wire or thelike must be performed by a too] similar to that described herein, it

' is necessary that the jaws of members 22 and 24 maintain apredetermined pivotal relationship with respect to each other for any ofthe various angular positions of one member with respect to the otherone otherwise it will not be possible to grip or hold an object with theproper amount of force to permit positioning or tensioning in the mannerdesired. It is recognized that this feature, in and of itself, is notnew due to the disclosure contained in US. Pat. No. 2,596,767. However,this feature in combination with the nonfrictional rigidizing of a pivotcolumn with respect to one of a pair of pivotally mounted members whileat the same time permitting said pivot column to rotate with respect tothe other of said pivotally mounted members produces unique andbeneficial results heretofore unobtainable.

The tool 20' shown in FIG. 11 is similar in every respect to the toolshown in FIG. 6 except for the incorporation of a generally annularfrustoconically shaped bushing 56, see also FIG. 12, which is disposedintermediate the nut portion 40' of pivot column 36' and member 24'. Thebushing 56 is formed from a material having a low coefficient offriction such as tetrafluoroethylene. The purpose for using the bushing56 is to control, at least in part, the maximum amount of operating themembers relative to the other of said members. v

In view of the foregoing, it will be readily appreciated that a toolhaving a joint constructed in accordance with the invention describedherein is easily adjustable for wear or for feel" for any degree oftightness. Further, such adjustability may be achieved through the useof a single tool since the nut portion is nonfrictionally rigidized withrespect to one of said members. In addition, it will also be understoodthat the turning resistance of the pivot is constant through the fullarc of movement; adjustment for the degree of tightness with which themembers are held together can be made without disassembly of the tool;no change of alignment of parts occurs as a result 'of any suchadjustment; the nut portion of the pivot column will neither loosen nortighten from pivotal operation of the members; the joint is durable inconstruction; the tool is easily assembled and disassembled in a matterof seconds; and all parts are autoclavable or will withstandsterilization.

It is to be understood that this invention is not limited to the exactembodiments of the devices shown, which are merely by way ofillustration and not limitation, as various other forms andmodifications will be apparent to those skilled in the art; e.g. thetool-receiving means can be formed upon the nut portion of the pivotcolumn and the boss means may be formed upon the screw portion of thepivot column, and it is therefore intended that the appended claimscover all such changes and modifications.

I claim:

1. A controllable torque, pivotal joint suitable for use in a toolformed of a pair of longitudinal members that include handles at one endand tool elements at the other end, the pair of longitudinal membersbeing pivotably joined intermediate their ends, said controllabletorque, pivotal joint comprising:

A first frustoconically shaped bore, including at least one internaloutwardly projecting recess, formed in one of said pair of longitudinalmembers;

a second frustoconically shaped bore formed in the other of said pair oflongitudinal members, the longitudinal axes of said first and secondfrustoconically shaped bores being concentrically disposed with respectto one another, said first and second frustoconically shaped bores beingformed so that their smaller ends face one another when said pair oflongitudinal members are pivotably joined;

a frustoconically shaped screw mounted in said first frustoconicallyshaped bore, said frustoconically shaped screw including an undercutthreaded stud formed along the longitudinal axis of said firstfrustoconically shaped bore and projecting into said secondfrustoconically shaped bore along the longitudinal axis thereof; and,

a frustoconically shaped nut mounted in said second frustoconicallyshaped bore for rotation with respect to said second frustoconicallyshaped bore, said frustoconically shaped nut including at least one bossformed so as to fit into said at least one outwardly projecting recessin said first frustoconically shaped bore so as to prevent rotationalmovement of said frustoconically shaped nut with respect to said firstfrustoconically shaped bore, said frustoconically shaped nut including athreaded aperture formed along the longitudinal axis of said secondfrustoconically shaped bore, the threaded stud portion of saidfrustoconically shaped screw being screwed into said threaded aperturein said frustoconically shaped nut so as to maintain said pair oflongitudinal members in pivotal relation with respect to one another,the surface of said frustoconically shaped nut facing toward said firstfrustoconically shaped bore and the frustoconically shaped portion ofsaid frustoconically shaped screw being separated from said firstfrustoconically shaped bore and the frustoconically shaped portion ofsaid frustoconically shaped screw so that the only contacting surfacebetween said frustoconically shaped nut and said frustoconically shapedscrew is the threaded region where said frustoconically shaped screw isscrewed into said frustoconically shaped nut whereby the torque at saidpivotal joint is controlled by the amount of thread of saidfrustoconically shaped screw that is screwed into saidthreaded aperturein said frustoconically shaped nut. 2. A pivotal joint suitable for usein a tool as claimed in

1. A controllable torque, pivotal joint suitable for use in a toolformed of a pair of longitudinal members that include handles at one endand tool elements at the other end, the pair of longitudinal membersbeing pivotably joined intermediate their ends, said controllabletorque, pivotal joint comprising: A first frustoconically shaped bore,including at least one internal outwardly projecting recess, formed inone of said pair of longitudinal members; a second frustoconicallyshaped bore formed in the other of said pair of longitudinal members,the longitudinal axes of said first and second frustoconically shapedbores being concentrically disposed with respect to one another, saidfirst and second frustoconically shaped bores being formed so that theirsmaller ends face one another when said pair of longitudinal members arepivotably joined; a frustoconically shaped screw mounted in said firstfrustoconically shaped bore, said frustoconically shaped screw includingan undercut threaded stud formed along the longitudinal axis of saidfirst frustoconically shaped bore and projecting into said secondfrustoconically shaped bore along the longitudinal axis thereof; and, afrustoConically shaped nut mounted in said second frustoconically shapedbore for rotation with respect to said second frustoconically shapedbore, said frustoconically shaped nut including at least one boss formedso as to fit into said at least one outwardly projecting recess in saidfirst frustoconically shaped bore so as to prevent rotational movementof said frustoconically shaped nut with respect to said firstfrustoconically shaped bore, said frustoconically shaped nut including athreaded aperture formed along the longitudinal axis of said secondfrustoconically shaped bore, the threaded stud portion of saidfrustoconically shaped screw being screwed into said threaded aperturein said frustoconically shaped nut so as to maintain said pair oflongitudinal members in pivotal relation with respect to one another,the surface of said frustoconically shaped nut facing toward said firstfrustoconically shaped bore and the frustoconically shaped portion ofsaid frustoconically shaped screw being separated from said firstfrustoconically shaped bore and the frustoconically shaped portion ofsaid frustoconically shaped screw so that the only contacting surfacebetween said frustoconically shaped nut and said frustoconically shapedscrew is the threaded region where said frustoconically shaped screw isscrewed into said frustoconically shaped nut whereby the torque at saidpivotal joint is controlled by the amount of thread of saidfrustoconically shaped screw that is screwed into said threaded aperturein said frustoconically shaped nut.
 2. A pivotal joint suitable for usein a tool as claimed in claim 1 including a hollow, frustoconicallyshaped bushing formed from a material having a low coefficient offriction, said bushing being disposed between said frustoconicallyshaped nut and said second frustoconically shaped bore.